Abstract: Natural Neon of Xi’an area was quantitatively analyzed by lowering impact electron energy in EI ion source. Impact electron energy was set to 43.5 eV to eliminate the ⁴⁰Ar²⁺ interference with ²⁰Ne⁺. Based on this core parameter，other parameters of EI ion source were optimized. Then online isotope dilution method was used to analyze natural neon of Xi’an area for five times, the relative standard deviation was 0.6% and the average value accords with the reported data in 2%. So this eliminating interference method can be used to quantitatively analyze neon.